1. Field of the Invention
The present invention pertains to techniques for enhancing exchange processes between two fluids. More particularly, the present invention relates to packing elements and systems for use in exchange chambers, such as utilized in mass transfer or heat exchange processes, for example.
2. Description of Prior Art
Many commercial chemical and other processes involve mass transfer or heat exchange, and utilize packed columns or chambers to carry out these steps. Such processes can include distillation, absorption and desorption, gas cleaning and drying, and various biological processes, such as filtrations. Two fluids, usually a gas and a liquid (although two liquids may be utilized) are intermingled within a chamber, typically as counter-current flow streams wherein the two fluids move generally in opposite senses along the same flow axis. In a co-current system, the two fluids move generally in the same senses along a single flow axis; a cross-current facility features the two fluids moving along separate intersecting flow axes.
The mass transfer rates and/or the reaction rates of the processes increases with increasing amounts of effective surface area that can be wetted by liquid within the chamber and over which the two fluids can then interface with one another. Packing elements are placed in the chamber to increase the amount of surface area available for such interfacing. One type of packing system that has been used includes a multi-layered construction of parallel, corrugated plates.
The plates are generally made of woven sheet or solid sheet and are placed in contact with one another such that the corrugations, or ridges and grooves, are at an angle to a general flow direction while the plates themselves are disposed in planes parallel to such a direction. Consequently, the fluid flow is deflected from the general flow direction, and may result in non-uniform distribution of a liquid at various points along its general flow path. Such non-uniformity can be a severe disadvantage in an exchange process wherein uniform distribution is essential when one of the fluids is a gas.
A further disadvantage of the corrugated-plate packing elements is due to the tendency of liquid to flow down the corrugations rather than evenly coating the plate surfaces while flowing from corrugation to corrugation. Such "channeling" may significantly decrease the exchange efficiency due to low degree of fluid mixing and reduced interfacial area.
It is advantageous and desirable to provide a packing technique to enhance the opportunity for interaction between two fluids in an exchange process by reducing channeling effects of liquid flow, increasing the wetted surface area for fluid-fluid interaction, reducing the resistance to gas flow and generally increasing the intermixing and mutual exposure between two fluids in the exchange process. The present invention provides a technique to accomplish these ends.